Process for inhibiting corrosion in oil and gas wells



PROCESS FOR INHIBITIN G CORROSION IN OIL AND GAS WELLS Arthur F. Wirtel,Glendale, and Charles M. Blair, Jr.,

Webster Groves, Mo., assignors to Petrolite Corporatlonywilmington,Del., a corporation of Delaware No Drawing. Application April '1, 1953Serial No. 346,264

1 Claim. (Cl. 252-855) This invention relates to the inhibition ofcorrosion of metals. It includes new compositions for use in preventingcorrosion of metals, in particular, iron, steel, and ferrous alloys, andthe process of preventing such corrosion by application of the newcompositions to the surfaces of the metals. The invention is ofparticular value in the prevention of corrosion of pipe or equipmentwhich is in contact with corrosive oil-containing media as, for example,in oil wells producing corrosive oil or oil-brine mixtures, in oilrefineries, and the like, but it is useful in numerous other systems orapplications, as the new compositions appear to possess properties whichimpart to metals resistance to attack by a'variety of corrosive agents,such as brines, weak inorganic acids, organic acids, CO H 8, etc.

A wide range of corrosion inhibitors, particularly for.

use in oil and gas wells, oil refineries and the like, have heretoforebeen used or suggested for use. One group is that which includes amines,amido-amines and nitrogen heterocyclics characterized by the presence oftwo or more nitrogen atoms, at least one of which is basic, and one ormore hydrocarbon groups having from 8 to 32 carbon atoms. Such compoundshave a moderately strong nitrogen-containing basic group (either free orin salt form), which may be present as part of a heterocyclic ringstructure, as in certain amidine, e.g., imidazoline,tetrahydropyrimidine and carbamyl compounds, or not, as in non-cyclicamino amides or polyamines. There is a substantial variation in therelative eifectiveness of such agents as corrosion inhibitors. Ingeneral, we have found that the more complex products having a pluralityof basic nitrogen atoms, and in particular relatively complexamino-amides, imidazolines, tetrahydropyrimidines and carbamylderivatives of cyclic amidines are more efiective than simpler aminocompounds.

The present invention is based upon the discovery that the anticorrosiveaction of such agents, as a class, is markedly enhanced if they areassociated with an alkylated aromatic sulfonic acid of the typehereinafter defined, or a salt thereof. We have no explanation of thisobserved result, as in our tests, we have not found that the alkylatedaromatic sulfonic'acids which we use, or

their salts, have any marked corrosion inhibiting action.

On the other hand, we have found corrosion inhibitors, which when usedconventionally reduce corrosion very substantially, have their corrosioninhibiting action markedly enhanced by admixture with about 50% of analkylated aromatic sulfonic acid salt. Thus, in one instance, we. foundthat a known corrosion inhibitor (a mixture of monoand diimidazolinesobtained by heating 384 pounds of tall oil and 146 pounds of triethylenetetramine for 2 /2 hours at 285 C., which possibly contained a minorproportion of amides in addition to the imidazolines) when injected atthe rate of 2 gallons a week into a gas-distillate well reduced the ironcontent of water from the flow line at the surface from about 240 p.p.m.to 50-60 p.p.m. With this same inhibitor, injected at the samcrate,butjn admixture. with about 36 its weightof ammonium diisopropylnaphthalene sulfonate, the iron content of the water was reduced toabout 10-15 p.p.m. In both cases, suitable solvents were used and theinhibiting composition was introduced. down the annulus between thecasing and the tubing. .The ammonium diisopropyl naphthalene sulfonatehad no substantial corrosion inhibiting properties.

Thus, the new compositions of the invention consist of admixtures of (1)a corrosion-inhibiting agent characterized by having at least twonitrogen atoms, at least one of which is basic, which may be aminogroups or form portions of heterocyclic ring structures and at least onehydrocarbon group having 8 to 32 carbon atoms, with (2) an alkylatedaromatic sulfonic acid, which may be represented by the formula s0;cation in which R is an alkyl radical having 3 to 12 carbon atoms, n isa number from 1 to 3, and with the requirement that the total number ofcarbon atoms present in (R),, is at least 6, or the formula p S 03cation or the cation of a water-insoluble amine, such as amyl amine,cyclohexyl amine, benzyl amine, amines derived from higher fatty acidshaving 8 to 18 carbon atoms, such t as lauryl amine or the mixed aminesderived from fats or oils, Which are commercially available, or othercation, including polyamines or the like, such as ethylenediamine,

in which case the polybasic ion can be combined with one or moresulfonic acid groups up to a ntunber equal to its number of basicgroups, e.g., in the case of ethylene diamine, either one or two moles,or some intermediate amount, of sulfonic acid per mole of diamine.cation is hydrogen it is possible that this agent may form salts withthe corrosion-inhibiting amine, but in most,

instances, we think that the corrosion inhibiting amine and the sulfonicacid or'sulfonate will be present in simple admixture, as the corrosioninhibiting amine will generally, and advantageously, be used in the formof a salt, as will the sulfonic acid.

In addition to these two essential constituents of the new compositions,there will normally be present addi- 1 tional conventional materials,such as solvents where the admixtures are to be used in liquid form,waxes or other solidifying agents where the products are to be used insolid stick form, and waxes or othersolidifying agents and a weightingmaterial, such as barium sulfate or lead oxide, where the compositionsare to be used The use of corrosion inhibitors, particularly for oil and'gas well treatment, in liquid form, or in stick form with or withoutweighting in the form of weighted sticks.

agents, is conventional and well known, and the present invention isconcerned, not with the form of application of the compositions, butwith the enhancement of the corrosion inhibiting action of thenitrogen-containing agent by association therewith of the specifiedalkylated aromatic sulfonic acid.

In general, we have found that minor proportions of It can be hydrogen,sodium, potassium, am-

Ifthe J) the alkylated aromatic sulfonic acid based on the corrosioninhibiting compound "are adequate to produce marked'enhancement oftheactivity of the composition. Thus, 10% or less of an ,alkylatedaromatic sultonic acid, based on the inhibitor, produces amarked efiect.At present, we are not aware of any requirement as to an upper, limit.It, so far as we are aware, will be fixed byceconornic considerations,as useof an excess of an alkylated aromatic sulfonic acid does notreduce the enhahcement of the anticorrosion activity, nor do amounts in,excess of S to 100%, based on the corrosion inhibitor, appear toincrease the enhancement beyond that obtained with to At worst, anexcess serves as an additional diluent. Thus, the range we contemplateis fr om about 5%, to about 100% of the alkylated aromatic sulfonicacid, based onth'e corrosion inhibitor, but it is tojbe understood thatuse ,oflarger, amounts, does. not

involve departure from the invention,

As previously stated, the corrosion inhibitors used in the newcompositions are characterized by the presence of (1) at least onehydrocarbon group, having 8 to 32 carbon atoms, and (2) at least twonitrogen atoms, of which at least one is basic, which may be present aspart of, a heterocyclic ring structure ornot, In certain of the mosteffective inhibiting agents, basic nitrogen atoms amino groups, e.g.,the high boiling residue from the preparation of ethylene diamine andthe like. A .num-

ber of such compounds are known to serve as corrosion inhibitors. We,have found that, as a class, their corrosion inhibiting. etficiency isenhanced by associating them with an alkylated aromatic sulfonic acid ofthe type described above. We shall give illustrations of suit ablecorrosioninhibiting compounds by reference to various patents and patentapplications in which theyare described, it being understood that thepresent application is based on the discovery of the enhancement of thecorrosion inhibition exhibited by these compounds, rather than in thecompounds themselves.

'A particularly effective group of corrosion inhibiting agents are thosedescribed in Patent Re. 23,227, Blair and Gross. These compositions arecyclic amidines, particularly imidazolines characterized by having atleast one hydrocarbon group containing 8 to 32 carbon atoms. Thecompositions may, and advantageously do, have in addition to the twonitrogen atoms which form part of the cyclic structure additionalbasicnitrogen atoms prescut as part of a side chain linked to one of the ringnitrogen atoms, as where the products are derived from triethylenetetramine, tetraethylene pentamine, or the high boiling residues fromthe production of these compositions, having 6, 7 or even more aminogroups. The compositions of this patent constitute one class ofcorrosion inhibitors which is usefully employed in preparing thecompositions of the present application Typical useful compounds ofthistype include:

2-undecy1imidazo1ine; Z-heptadecylimidazoline;

2-pentadencyl, l-heptylimidazoline;

2-octyl, 1-hydroxyethylirnidazoline;

2-nonyl, l-decylimidazoline; 2 o1eylimidazoline;

Z-cyclohexylethyl, l-methylimidazolinet. zabietyl,l-ethyloxyethylimidazoline;r l-octadecylimidazoline;

Z-methyl, l-octylimidazoline; l-dodecyloxymethyl,2-hydroxyrnethylimidazoline;,. l-oleoyloxyethyl,2-chloromethylimidazoline; 1-N decylaminoethyl, 2-ethylimidazoline;l-abietyl, Z-phenylimidazoline; i%9la? rl minqe h limiqazolin n iZ-heptadecyl, l-diethylenediaminoimidazollne; Z-methyl,1-hexadecy1aminoethylaminoethylimldazoline;l-dodecylaminopropylirnidazoline;l-stearoyloxyethylaminoethylimidazoline; Z-ethyl, 1-(N,N dodecyl,hydroxyethyl)aminoethylimidazoline;1-steararnidoethylaminoethylimidazoline; 1- (N-dodecyl)-acetarnidoethylarninoethylimidazoline; Chloroparafiin alkylationproduct of l-arninoethyl, 2-

methylimidazoline.

Application Serial No. 227,944, filed May '23, 1951, Blair and Gross,now U.S. Patent No. 2,640,029, dated May 26, 1953, describes, ascorrosion inhibitors, substituted tetrahydropyrimidines of the formulatype:

/N?CB5 where a D isamember of; the class consistingiof, D--.R and l i;represents a divalent organic radical containing less than 25 carbonatoms, composed of elements from the group consisting of C, H, O, andN;R isa member of the class consisting of hydrogen and hydrocarbonradicals, with ;the proviso that at least one; occurrence, of R containsfrom 8 to 32 carbon atoms; B is amember of the class consistingofhydrogen and hydrocarbon radicals containing less than 7 carbon atoms,with the proviso that at least threeoccurrences-of Bjbe, hydrogen.Typical su bstituted tetrahydropyrimidines of this ,type include:

Z-undecyl, 4-methyltetrahydropyrimidine;

l-ethyl, 2-octyl, 4-dimethyl, 6-cyclohexyltetrahydropyrimidine;

.Z-heptadecyl, 6-methyltetrahydropyrimidine;

Z-abietyl, 4,6-dimethyltetrahydropyrimidine;

2-naphthylmethyl, 1-butyltetrahydropyrimidine;

2cyclohexylethyl, 1,6-dimethyltetrahydropyrimidine;

l-octadecyl, 2-methyltetrahydropyrimidine;

1-oleylamidoethyltetrahydropyrimidine;

l-stearoyloxyethyl, 4-phenyltetrahydropyrimidine;

Z-heptadecenyl, 1-arninopropyltetrahydropyrimidine;

Chloroparatfin alkylation product of l-arninopropyl, 2-

methyltetrahydropyrirnidine;

l-dipropylenediamino, 2-cyc1opentylpropyltetrahydropyrimidine.

Application Serial No. 317,596, filed, October 29, 1952,

now abandoned, Blair, describes as corrosioninhibitors oxyethylatedimidazolines; such ascompoundsof the sisting of hydrogen andaliphaticand cycloaliphatic hydro carbon radicals; with the proviso that at leastone occurrence of R contains 8 to 32 carbon atoms.examplesofsuchcompounds having corrosion inhibiting properties include.the products obtained by adding from Typical 2 to v20. moles ofethylene oxide 'per mole to the following'imidazolines, as described insaid apphcationz 2-undecylimidazoline;

Z-heptadecylimidazoline;

2-oleylimidazoline; I

2-heptadecyl, 4,5-dimethy1imidazoline; 2-heptadecyltetrahydropyrimidine;

Z-hydrdxyethyl, 5-ethyl, l-decyltetrahydropyrimidine; l-aminoethyl,2-heptadecylimidazoline; l-diethylenediamino, 2-heptadecylimidazoline;l-triethylenetriamino, 2-ethylheptadecylimidazoline; l-aminoethyl,Z-undecylimidazoline; l-diethylenediamino, 2-undecylimidazoline;l-triethylenetriamino, Z-undecylimidazoline; l-aminoethyl,2-pentadecylimidazoline; l-diethylenediamino, 2-pentadecylimidazoline;

- l-triethylenetriamino, Z-pentadecylimidazoline;

l-aminoethyl, 2-nonylimidazoline;

l-diethylenediamino, 2-nonylimidazoline;

l-triethylenetriamino, Z-nonylimidazoline;

l-aminoethyl, Z-heptadecylenylimidazoline;

l-diethylenediamino, 2-heptadecylenylimidazoline;

l-triethylenetriamino, Z-heptadecylenylimidazoline;

lv-aminoethyl, 2-undecylenylimidazoline;

l-diethylenediamino, 2-undecylenylimidazoline;

l-triethylenetriamino, Z-undecylenylimidazoline;

l-aminoethyl, 2-hydroxyheptadecylenylimidazoline;

l-diethylenediamino, 2 hydroxyheptadecylenylimidazoline;

l-triethylenetriamino, 2 hydroxyheptadecylenylimidazoline;

l-aminoethyl, Z-abietylimidazoline;

l-diethylenediamino, Z-abietylimidazoline;

l-triethylenetriamino, Z-abietylimidazoline;

l-aminoethyl, 2-cyclohexylethylimidazoline;

l-diethylenediamino, 2-cyclohexylethylimidazoline;

l-triethylenetriamino, 2-cyclohexylethylimidazoline;

l-aminoethyl, 2-naphthenylimidazoline;

l-diethylenediamino, Z-naphthenylimidazoline;

l-triethylenetriamino, Z-naphthenylimidazoline;

l-aminopropyl, 2-heptadecyl(methy1*)imidazoline; *in 4 or 5 positionl-aminopropylaminopropyl, 2 haptadecyl(methyl*)imidazoline; *in 4 or 5position l-aminopropyl, 2 heptadecylenyl(methyl*)imidazoline;

*in 4 or 5 position l-aminopropylaminopropyl, 2 heptadecylenyl(methyl*)imidazoline; *in 4 or 5 position l-aminopropyl,2-undecylenyl(methyl*)imidazoline; *in

-4 or 5 position 1-aminopropylaminopropyl,2-undecylenyl(methyl*)imidazoline; *in 4 or 5 position l-aminopropyl,2-abietyl(methyl*)imidazoline; *in 4 or 5 positionl-aminopropylaminopropyl, 2 abietyl(methyl*)imidazoline; *in-,4 or 5position Laminopropyl;2-naphthenyl(methy1*)imidazoline; *in 4 or 5position l-aminopropylaminopropyl, 2-naphthenyl(methy1*)imidazoline; *in4 or 5 position Application Serial No. 323,150, filed November 28,

1952, now abandoned, Blair, describes substituted carbonyl.

compounds containing at least two cyclic amidine radicals which areusefully used in preparing compositions of the invention, these beingcompounds in which the cyclic amidineradical is of the structure whereinR is a hydrocarbon radicalcontaining from 7 t9 ;3.1 carbon atoms; n isthe numeral 2,- t0 3 inclusive; R;

is a member of the class consisting of hydrogen atoms and lower alkylradicals; R is a member of the classthe final compositions, being unitedthrough amino nitrogens of the radicals X by at least one member of the:

class consisting of +=Og (::=s; ilJ=NH and radicals. Typicalcompositions of this type include compositions wherein l-aminoethyl,2-heptadecyltetrahydropyrimidine is coupled'with urea;

l-aminopropyl, 2-heptadecyltetrahydropyrimidine is coupled with biuret;

l-dipropylenediamino, Z-heptadecyltetrahydropyrimidine is coupled withurea;

l-aminoethyl, 2-undecyltetrahydropyrimidine is coupled with guanidinecarbonate;

l-aminopropyl, 2-undecyltetrahydropyrimidine is coupled with biuret;

l-dipropylenediamino, 2-undecyltetrahydropyrimidine is coupled withurea;

l-aminoethyl, 2-decylenyltetrahydropyrimidine is coupled with thiourea;

l-aminopropyl, 2-decylenyltetrahydropyrimidine is coupled with urea; I

l-dipropylenediamino, 2-decylenyltetrahydropyrimidine is coupled withbiuret;

l-aminoethyl, Z-heptadecylimidazoline is coupled with urea;

l-diethylenediamino,

with biuret;

l-triethylenetriamino, 2-pentadecylimidazoline is coupled with guanidinecarbonate;

l-aminoethyl, Z-undecylenylimidazoline is coupled with thiourea;

l-diethylenediamino, Z-undecylenylimidazoline is coupled with urea;

1-triethylenetriamino, 2-undecylenylimidazoline is coupled with biuret;

l-aminoethyl, 2-hydroxyheptadecylenylimidazoline is coupled withthiourea;

Z-heptadecylimidazoline is coupled l-aminoethyl,2-cyclohexylethylimidazoline is coupled with urea;l-triethylenetriamino, Z-abietylimidazoline is coupled with thiourea; 1I l-aminoethyl, Z-naphthenylimidazoline is coupled with urea.

Patent 2,598,213, May 27, 1952, Blair, describes as corrosion inhibitorsbasic amides of polyamines characterized by the presence of an acylradical of a carboxy acid having 8 to 32 carbon atoms and at least onebasic amino nitrogen atom, that is, an amino radical charac- 7. surereaction of ethylene dichloride and ammonia; the amide from 300partsofricinoleic acid andithe same mixture of bases; .the amide from 100partsby weight ofi'olive oil and 100 parts by weight of diethylene triamine;the amide from 310 parts by-wei'ght of the ethyl ester of oleic acid and286 parts by weight of triethylene tetramine; corresponding amides frompurified naphthenic acids and from the carboxy acids derived by theoxidation-oi Pennsylvania crude oil; the amide from 284 parts of stearicacid and 74 parts of 1,2-propylene diamine.

Other effective inhibitors are the higher alkyl diamines such asN-octadecylpropylene diamine, and similar polyamines obtained bytreating the monoarnines correspond ing to naturally occurring fattyacids or other monocarboxy detergent-forming acids with acrylonitrilefollowed by hydrogenation to convert the nitrile group to an aminogroup. We have found the corrosion inhibiting properties of suchcompounds are enhanced when they are incorporated in compositions of thepresent invention.

From the foregoing it will be noted that there are a number of compoundscharacterizedbythe presence ofat least two nitrogen atoms, at least oneof which isbasic, and a hydrocarbon group having 8 to 32 carbon atomswhich have corrosion inhibiting properties,- andwhich have theirefiectiveness substantially increased by association with an alkylatedaromatic sulfonic acid of-the type described above. The effectiveness-ofthe corrosion inhibitors varies, some being considerablymore effectivethan others, and so far as we areaware; there will be variation ineffectiveness of the compositions of-the invention more or less parallelto the variationsineffectiveness of the corrosion inhibitors per setWebelieve that the most effective of the corrosion inhibitors are thecomplex cyclic amidines, in particularthe substituted glyoxalidinesdescribed in Patent Re. 23,227, and the corn plex amidines described inapplications Serial Nos. 227,944, 317,596 and 323,150, together with theamino amide products described in Patent 2,598,213..

We have heretofore referred to the fact that the new compositions of theinvention may be used in liquid form, usually with the use of anappropriate solvent such as a mixture of high boiling aromatichydrocarbons and medium boiling paraffinic hydrocarbons or may be usedin stick form with or Without weighting agents. The use of corrosioninhibitors in stick form and in weighted stick form, the purpose. ofproviding them in such form, and the preparation of products in suchform is well known. See, for example, Patents 2,599,384 and 2,599,385,June 3, 1952. The compositions of the present invention may be used as.the corrosion inhibiting constituents of weighted solid stick inhibitorsas described'in these patents or of non-weighted solid stick inhibitors.

The invention will be further illustrated by the following specificexamples in which typical compositions of the invention are described.In each of them, we have found that the corrosion inhibiting action ofthe corrosion inhibitor is markedly enhanced by the alkylated aromaticsulfonic acid associated with it. This enhancement is also found withthe wide range of inhibitors described above and the examples are,therefore, given purely by way of illustration and not by way oflimitation.

Example I tion, 12 lbs. of anhydrous glycolic acid were added slowly.Finallyy IOO-lbss of a -50%- (by wti) solution of am.

monium" diisopropylunaphthalenesulfonatein an -20 mixture of aromaticgas .oil' and isopropyl alcohol were added while stirring. The finishedcompound was a thin oil.

Example ll 384 lbs. of tall oil and-1461 lbs. of triethylene tetraminewere reacted for 2 /2 hrs. at 285 C., as described in Example I.Approximately 41.5 lbs. of water were evolved and condensed from theautoclave. The product consisted of a mixture of monoand diimidazolineswith minor proportions of substituted amides of tall oil fatty acids. Tolbs. of-this product-were added 191 lbs. of aromatic gas oil and,.whilestirring, 9 lbs. of 66 Baum sulfuric acid; at. such a rate -as tomaintain a temperature of less than 100 C. and. above 80 C.

Some heat may be rapplieddf necessarylto maintain this temperature. 100lbs. of a- 50% (by'wt.) solution of ammonium diisopropyl T naphthalenesulfonate in an 80-20 mixture of commerciah xylene and isopropyl alcoholwere added: to the above and the whole stirred until homogeneous;

Examplelll 50 lbs. of ammonium diisobutyl naphthalene sulfonate weresubstituted for the ammonium diisopropyl naphthalene sulfonateof ExampleII.

Example 1V 501bs.: of the cyclohexylamine salt ofi diisobutylnaph--thalene sulfonic acid were substituted for the ammonium diisopropyl.naphthalene. sulfonate of Example 11.

Example V with stirring, lbs. of kerosene, 20 lbSrOf' linoleic acid, and50 lbs. of cyclohexylammonium.dodecylbenzene sulfonate Example VI Asolid-stick type corrosion inhibitor with improved activity was preparedby casting the homogeneous melt resulting from mixing thefollowingingredients at 100 120 C.:

Corrosion inhibitor of Example V lbs.. 50 Ammonium diisopropylnaphthalene sulfonate ..lbs 10 Microcrystalline wax of 186 F. M.P....lbs 40 Oxidized microcrystalline wax of 185 F. M.P. and

60 saponification value lbs 20 The solid product has a density of about0.93 at 25 C.

Example VII A solid stick type corrosion inhibitor of high densityparticularly .useful in the treatment of'distillate wells prepared bycasting the melt resulting from mixing thoroughlythe followingingredients at'about 120 C.:

Product of Example VI -..lbs 38 Powdered barium sulfate lbs 62 The solidproduct had a density of about 2.0 and a softening point of about F.

Example VIII The sulfonic acid component of this composition wasprepared as follows:

600"'lbs. of a naphthenictype-crude oil (if-22 API gravity were run intoa lead lined sulfonating tank, equipped with stirrer, heater coils anddrain lines. While stirring and maintaining the oil at 35 C., 300 lbs.of 20% oleum were run into the oil over a period of 3 hrs. The mixturewas then stirred for an additional 30 minutes, heated to 90 C. andwashed by adding 20 gals. of water. After settling quietly for 4 hrs.,the acidic water layer was drawn off and the oil layer neutralized tothe methyl orange end point by addition, with stirring, of aqua ammonia(approximately 29% NH;.;).

100 lbs. of this component were mixed with 800 lbs. of the tall oilreaction product of Example II. This mixture was warmed to 80 C. andstirred until homogeneous.

The following is a typical illustration of the enhancement of thecorrosion inhibiting action obtained with the compositions ofthe presentinvention: i

Weighed plates of 1020 steel were rotated in a mixture of 55 ml. ofkerosene, and 250 ml. of a brine containing 2% sodium chloride, 0.2%sodium sulfate, 0.4% calcium chloride and 0.4% magnesium chloridehexahydrate. The stirring apparatus was maintained at a temperature of100 F. in a controlled atmosphere of 0.25 atmosphere of hydrogen sulfideand 0.75 atmosphere of nitrogen. The plates were rotated for a period of72 hours, after which they were removed, dipped briefly in inhibited HClto remove ferrous sulfide, washed, dried and weighed to determine lossof metal. Parallel tests were run using no inhibitor, using 160 partsper million of the tall oil reaction product of Example II, using 160parts per million of the same inhibitor with 16 parts per million ofammonium diisopropyl naphthalene sulfonate, using 160 parts per millionof the same inhibitor and 40 parts per million of the same sulfonate,using 160 parts per million of the same inhibitor and 80 parts permillion of the same sulfonate, and using no inhibitor but 160 parts permillion of the same sulfonate. The average weight loss from tests run inquadruplicate showed 241 mg. with no added agent, 185 mg. with thesulfonate only, 43 mg. with the inhibitor only, 16 mg. with theinhibitor plus 16 parts per million of sulfonate, 20 mg. with theinhibitor plus 40 parts per million of the sulfonate and 14 mg. with theinhibitor plus 80 parts per million of the sulfonate. Similar resultswere obtained in other laboratory tests using various brine-oilcombinations, various corrosive atmospheres, and various combinations ofinhibitor and sulfonate.

In another test, carried out under the same conditions, but with a 48hour test period, the weight loss of the 1020 steel plates was 166 mg.with no added agent, 164 mg. with 40 parts per million of ammoniumdiisopropyl naphthalene sulfonate, 35 mg. with 40 parts per million ofN-aminopropyloctadecylamine, 17 mg. with 40 parts per million of thissame amine and 7 parts per million of the sulfonate, 17 mg. with 40parts per million of the amine and 30 parts per million of the sulfonateand 16 mg. with 40 parts per million of the amine and 40 parts permillion of the sulfonate.

The effectiveness of the compositions in the field was shown by theresults of a test in a gas distillate well in the Gwinville field inMississippi. This well produced three million cubic feet of gas, 40barrels of liquid hydrocarbon and five barrels of salt water a day.Before treatment, water trapped from the flow line at the surface showedan iron content of about 240 parts per million. 2% gallons of the talloil reaction product of Example 11, dissolved in 7 /2 gallons ofhydrocarbon condensate were introduced down the annulus between thecasing and the tubing once each week. It flowed down the annulus, becamemixed with the produced fluids at the bottom of the hole and was carriedup the tubing to the surface by the gas flow. After several weeks ofsuch treatment, the water from the flow line had an iron content of 50-60 parts per million. 2 /2 gallons of the prod- 10 net of Example IIwere then substituted for this inhibitor, and used in the same way.After three weeks, the water was found to have an iron content of 10-15parts per million.

In the foregoing we have referred at length to the inhibitors which areused as being compounds having at least two nitrogen atoms, at least oneof which is basic, and at least one hydrocarbon group having 8 to 32carbon atoms. It is to be understood that these compositions may be usedin the form of the free bases, or in partially neutralized form or incompletely neutralized form, and such partial or complete neutralizationmay be by means of an inorganic acid, such as sulfuric acid, or anorganic acid, such as acetic acid, gluconic acid, a higher fatty acid orany of the acids which are used for neutralizing basic amino corrosioninhibitors, in accordance with usual practice.

An additional advantage in the use of the new compositions which we haveobserved is a substantial and unexpected decrease in certainemulsification problems sometimes encountered. Thus, when corrosioninhibitors of the type used in the compositions of the invention areincorporated in hydrocarbon-water systems where the hydrocarbon isrelatively pure, i.e., is gasoline, kerosene, distillate, liquefiedpetroleum gases and the like, as contrasted with crude oil, there is atendency for oil-in-water emulsions to form. This tendency is greatlyreduced, or absent, when the new compositions are used. This issurprising, because the alkylated aromatic sulfonates, while known toresolve water-in-oil emulsions, have found no application asdemulsifiers for oil-in-water emulsions.

We claim:

The process of inhibiting corrosion of ferrous metals exposed tocorrosive agents normally present in producing oil and gas wells whichincludes introducing into the well a composition having corrosioninhibiting properties which contains, as an active corrosion inhibitingconstituent, a nitrogen-containing agent characterized by having atleast 2 nitrogen atoms, at least one of which is basic, and at least onehydrocarbon group having 8 to 32 carbon atoms and which contains, inadmixture therewith, as an agent which enhances the corrosion inhibitingactivity of the corrosion inhibiting constituent, at least 5% and notover based on the corrosion inhibiting constituent, of an alkylatedaromatic sulfonic acid compound selected from the class consisting ofalkylated naphthalene sulfonic acid compounds of the formula )n S03cation in which R is an alkyl radical having 3 to 12 carbon atoms, n isa number from 1 to 3, with the proviso that the total number of carbonatoms present in (R), 1s at least 6, and alkylated benzene sulfonic acidcompounds of the formula (R), SO; cation UNITED STATES PATENTS 2,493,483Francis et a1. Ian. 3, 1950 2,583,399 Wachter Jan. 22, 1952 2,618,608Schaefier Nov. 18, 1952 2,658,036 Core et a1. Nov. 3, 1953

1. THE PROCESS OF INHIBITING CORROSION OF FERROUS METALS EXPOSED TOCORROSIVE AGENTS NORMALLY PRESENT IN PRODUCING OIL AND GAS WELLS WHICHINCLUDES INTRODUCING INTO THE WELL A COMPOSITION HAVING CORROSIONINHIBITING PROPERTIES WHICH CONTAINS, AS AN ACTIVE CORROSION INHIBITINGCONSTITUENT, A NITROGEN-CONTAINING AGENT CHARACTERIZED BY HAVING ATLEAST 2 NITROGEN ATOMS, AT LEAST ONE OF WHICH IS BASIC, AND AT LEAST ONEHYDROCARBON GROUP HAVING 8 TO 32 CARBON ATOMS AND WHICH CONTAINS, INADMIXTURE THEREWITH, AS AN AGENT WHICH ENHANCES THE CORRISION INHIBITINGACTIVITY OF THE CORROSION INHIBITING CONSTITUENT, AT LEAST 5% AND NOTOVER 100% BASED ON THE CORROSION INHIBITING CONSTITUENT, OF AN ALKYLATEDAROMATIC SULFONIC ACID COMPOUND SELECTED FROM THE CLASS CONSISTING OFALKYLATED NAPHTHALENE SULFONIC ACID COMPOUNDS OF THE FORMULA